The invention concerns a method for the installation of roller bearings and an installation apparatus for roller bearings, in particular, angular ball bearings, for example, in wheel carriers of automobiles, airplanes, and the like.
Such roller bearings must be installed with an initial stress specified by the bearing manufacturer, so as to have the correct seat and so as to attain the intended service life. With a large number of mass-produced automobiles, the two roller bearings are in the immediate vicinity and their bearing surfaces are worked in an axial direction in such a way that they have the necessary initial stress with a flush installation.
With high-performance motor vehicles, in particular, with racing cars, however, the two roller bearings, mostly angularly moving ball bearings, have a considerable distance between one another, since with such motor vehicles, the tires have a great width and there could be inadmissible moments of tilt with ball bearings which are immediately adjacent. This makes it necessary to ensure the required initial stress in a manner other than the one which is common with mass-produced automobile manufacturing. Up to now one has had recourse to the great experience of installers, who were able to determine, with a few tests of the turning capacity of the bearings, whether the bearings, in accordance with the magnitude, have the correct initial stress or not. By the increasing use of ceramic materials with ball bearings, for example, for roller bodies, in particular balls, it has now become very important that this initial stress be maintained within narrow limits, since the bearing is otherwise damaged.
Apparatuses to measure the initial stress of a roller bearing or roller bearings, which simplify such a measurement, and that can all be used under the conditions of mass production manufacturing but cannot be carried out under usage conditions such as those which prevail during a race, are known from U.S. Pat. No. 6,070,325 A, U.S. Pat. No. 4,336,641 A, U.S. Pat. No. 5,718,049 A, and U.S. Pat. No. 4,054, 999.
The goal of the invention is to create an installation apparatus and an installation method, which makes it possible to easily inspect the initial stress of roller bearings during installation and thus to attain and maintain the correct initial stress prescribed by the manufacturer.
In accordance with the invention, this is done in that a length measurement gauge is placed against a stop at a known position in the axial area of one roller bearing in the interior of the hollow shaft; upon tightening the shaft nut against the bearing race of the other roller bearing, its axial shift with respect to the stop in the hollow shaft interior is determined, wherein when the shaft nut is tightened, a torque wrench is used, which permits the differentiation between the actual tension process of the roller bearing and the previous process to bring the shaft nut to a stop.
In this way, if the configuration and the material of the hollow shaft are known, which, in fact, is practically always the case, nowadays, through its construction, for example, via a finite element program, it is possible to determine the ratio between the longitudinal force and the elongation with sufficient accuracy, so as to arrive at the correct initial tension of the roller bearing with the measurement of the distance change of the length measurement gauge.
With only a torque wrench alone, it would not be possible to arrive at informative data because of the never reproducible ratios, on the one hand, between the shaft nut and thread and, on the other hand, between the shaft nut and the interior track of one bearing. However, the different torques upon turning the shaft nut to the roller bearing ring and the subsequent bringing about of the initial tension are sufficient, so as to take into consideration here only the length changes which go back to the initial tension process.